War fighting capabilities and methods have slowly evolved over the period of the twentieth century. One of many improvements has been a significant advance in the ability to deliver a weapon with great accuracy. Weapon delivery with zero or near zero circular error of probability [also referred to as circular error probable (“CEP”)] is almost the norm when the weapon is equipped with precision guidance capabilities.
In the military science of ballistics, circular error of probability is a simple measure of a weapon system's precision. The impact of munitions near the target tends to be normally distributed around the aim point with progressively fewer munitions located about the aim point at a greater distance away. A mathematician might characterize this pattern by its standard deviation, but a more intuitive method is to state the radius of a circle within which 50 percent of the rounds will land.
This movement for greater accuracy has been encouraged by the war fighter communities and has been made possible by technology growth. The World War I, World War II, Korean and Vietnam era warfare witnessed the application of massive use of unguided weapons with large chemically based explosive warheads. This approach was permitted because the size of the boundaries of the total set of acceptable targets was virtually unlimited (i.e., unlimited war) and the zone impacted by the chemically based warhead blast and shrapnel was normally within the CEP.
The geopolitical nature of warfare, however, has significantly evolved throughout the twentieth century and continues into the twenty first century. More specifically, changes in the set of all features that may form the list of acceptable targets has been driven by various influences. By way of example, FIG. 1 qualitatively illustrates a graphical representation of a target spectrum over the course of the twentieth century and the trend into the twenty first century.
The graphical representation of FIG. 1 includes a total set of features and objects that represents potential targets that may be subject to bombardment by a weapon. The total set may be subject to attack provided that there are no constraints such as technical, political, humanitarian, military or others. In reality, during the course of military history and especially in the twentieth century, the total set of features and objects has been reduced. Targets to the right of Line A are features and objects sensitive for political and humanitarian reasons. The targets sensitive for political and humanitarian reasons are exempt from attack without regard to any technical ability of any weapon or weapon system. For instance, the targets such as hospitals and religious shrines are adverse to collateral damage and off limits to long term lethal debris.
In a similar manner, features and objects above Line 1 are generally exempt from bombardment, not because of being unworthy, but because of technical, military or similar limitations or constraints. While the targets above Line 1 are often high value targets of military worthiness, the targets are hardened to attack with conventional weapons and often require ground attack or nuclear weapons. An example of early targets that fall within this region include well fortified bunkers such as bunkers designed by the Germans in World War II.
Thus, the set of targets that may be attacked by precision weapons incorporating chemically explosive warheads or lethal devices is reduced to that area enclosed by Line A and Line 1 of the target spectrum. Furthermore, in the late twentieth century the impact of social and political influences has given impulse to reducing the available set of targets by targeting constraints (to the left of Line B) and targets with low military value (below Line 2). The impact of the twenty first century influences (represented by Line B and Line 2) have further reduced the target region as defined by the twentieth century boundaries (represented within Line A and Line 1).
A strong contribution to the reduction of the target region has been the great improvement in guidance with the associated pin-point accuracy of the weapons (i.e., the exceedingly smaller CEP). The results of the blast and shrapnel region generated with a typical chemically based explosive often extends beyond the CEP. In contrast, there are some lightly defended targets which are not “hard,” but are simply of too little value to merit an individual attack. For example, a single tent would not be targeted in most of the conflicts of the twentieth century, unless it was associated with some other target such as an observation position or a command and control post. These targets, which are of too little value to warrant individual attention are represented below Line 2 in FIG. 1.
Likewise, there are some targets that require targeting and guidance beyond the capability of the war fighter. Prior to the advent of laser guided bombs, even relatively large targets, such as bridges, fell into this category when local defenses made low level bombing impossible. In Vietnam, some bridges were attacked with literally thousands of bombs without lasting effect, because the strike aircraft simply could not get close enough without exposure to great danger to place a bomb on a critical structural location. Most of these bridges were subsequently destroyed with the first attack by aircraft with laser guided bombs. These targets, which are not susceptible to attack because of the lack of adequate targeting information or due to lack of weapon placement precision, are shown to the left of Line B in FIG. 1.
Thus, with the growth of technical and political sophistication, social demands and economic pressures on war planners, a number of factors have changed the permissible target spectrum. Under these influences, the permissible set has shrunk while the innovative application of improved weapon systems has had the effect of expanding the target region. The net effect, however, is that the areas of growth have been more than offset by the areas lost.
There has been some modest growth in the target region below Line 1. For instance, bunker busters and other weapons have given strike planners the ability to strike harder targets. The term “bunker buster” is a generic term that generally applies to weapons that have the capacity to penetrate into targets that are deeply buried under ground, protected by thick layers of highly resistive materials such as concrete, and targets that are protected by considerable thickness (tens of meters) of overgrowth (e.g., earth, sand, or other natural material) prior to detonation of the explosive charge. The hardness beyond the capability of conventional weapons, however, is still on the order of tens of meters of concrete, and the absolute number of such targets is very small. Thus, changes in the boundary defined by Line 1 have an insufficient influence on the absolute number of targets that can be attacked.
Precision guidance and targeting by means of sophisticated sensors and intelligence tools has created a “zero CEP weapon.” It is now practical to assume that many weapons will “miss” their target by, for instance, inches, which is for nearly all purposes the same thing as a zero CEP. Thus, the area left of Line B has become smaller. While the improvement in technology has had some influence on the number of targets that can be attacked and has increased the target region somewhat, it has mostly changed the method of attack.
The area below Line 2 has become quite small. As non-state enemies have emerged as a threat, it has become necessary to target small soft targets such as individual automobiles or a single tent. This boundary shift has increased the target region somewhat, but the absolute number of targets that can be attacked has not been strongly influenced. At the same time, the area to the right of Line A has grown and, with conventional warheads, the blast radius is simply too large to allow most general purpose weapons to be used. This is the dominant effect in the rules of engagement for many conflicts of recent years. Foes who understand the political considerations of rules of engagement can protect their assets by locating them near, for instance, shrines, schools, and hospitals.
A couple of other factors should be recognized in accordance with the target spectrum of FIG. 1. First, a number of the targets are “too soft.” In other words, these targets are not susceptible to most forms of attack due to their lack of substance. A contact fuze will not generally function when a weapon contacts a tent. At shallow flight path angles, the weapon will simply pass through the tent, and will explode at some distance away. This problem is also seen with high velocity penetrators. In prior conflicts, the preferred means to attack soft targets was area munitions which may be a concussion weapon with a large blast radius of effectiveness, or a cluster weapon dispensing a large number of small explosives with very sensitive contact fuzes. These means are not generally acceptable for political reasons and the resulting unacceptable collateral damage.
Another factor is the need for flexibility. The nature of war has become much more dynamic and ad hoc as it applies to strike missions. In recent conflicts, the majority of strike platforms (e.g., ships, aircraft, troops, armored vehicles) did not know what specific targets with which they were to engage at the time of selecting munitions loading. Thus, the weapons carried to the conflict had to be general purpose, and it was highly desirable to have the effects of the weapons selectable to match both the target characteristics and the rules of engagement. In the process of prosecuting a campaign, matching weapons, targets, and rules of engagement is often impossible. As an example, Javelin (an anti-tank weapon) has been used to attack suburban structures, which is an inefficient match for the Javelin fuze and warhead. As a further example, cluster weapons have been used near civilian areas, resulting in injury to civilians who subsequently found unexploded ordnance. As yet a further example, Hellfire missiles (another anti-tank weapon) have been used to attack light trucks; a mismatch for the Hellfire fuze and warhead, which in some cases resulted in a failure to explode. In many other cases, the rules of engagement prevented a needed attack from being prosecuted, primarily due to the risk of collateral damage.
Thus, in some conflicts, the absolute space of targets has factually diminished. The change in war fighting methods and capabilities has not kept pace with this change in philosophy. The military continues to depend upon large chemically based explosives and cluster bombs with submunitions. Although precision guidance has offered a limited measure of performance gain to match these changes in philosophy, warhead and munitions characteristics continue to produce collateral damage, scatter latent lethal debris, and generate unacceptable over-kill.
A large class of warheads now used by various military establishments, including the United States Department of Defense, depends upon the conversion of certain chemical compounds into thermal energy, with dynamic pressure differentials and kinetic energy imparted to elements of the warhead (e.g., shrapnel) to produce lethal effects and destruction of a target. A proportion of this class of warheads contain the chemical compounds as a unified mass within a casing, also referred to as a unitary warhead. The substantial thermal effects, differential pressures and shrapnel of the unitary warhead can encompass a large area producing damaging effects to an area that exceeds that of the intended target thereby giving rise to the potential of inducing collateral damage. Additionally, unexploded unitary warheads (a class of unexploded ordnance) present a significant latent hazard. Intended and unintended motion, shock and impact imparted to or in proximity of an unexploded warhead can cause detonation with unintended damage, destruction, injury and death. Occurrences of the detonation of unexploded unitary warheads dating from World War I and World War II have been noted by the United Nations studies (see, for instance, www.unicef.org.vn/uxo.htm).
Another portion of warheads contain the chemical compounds in a substantially smaller container, herein referred to as submunitions, and of which multiple submunitions are packaged into a larger container. The submunitions are dispensed at the target to achieve lethal effects over an area. Dispensed submunitions, though effective, produce a certain number that fail to detonate for any number of reasons. These unexploded submunitions (a class of unexploded ordnance) present a latent hazard and collateral damage. Unexploded submunitions are known to detonate, causing severe injury and loss of life, when subjected to motion, shock and impact such as the motion, shock and impact that may be induced by the action of a person picking up the unexploded submunitions and then having it detonate. Additionally, unexploded submunitions present a hazard to one's own personnel that move through the area where the weapon has been dispensed, often present to remove and clear a dispensed area. The unexploded submunitions also present a hazard to innocent individuals that come into contact with the submunitions. Organizations and certain individuals have represented that the submunitions are equivalent to landmines and represent an unacceptable, dangerous element to society.
Another portion of warheads rely upon kinetic energy by way of substantial velocity imparted to dense materials properly shaped into suitable projectiles of sub-caliber and full-caliber dimensions to penetrate targets, also referred to as penetrating projectiles. Thermal effects, shrapnel and differential pressure are introduced into the target being derived from the high kinetic energy of the mass of the penetrating projectile. A portion of these penetration projectiles are typically formed from depleted uranium. Another portion of these penetrating projectiles are typically formed from shaped charges utilizing alloys of copper in a shaping cone. In current practice, the warheads employ velocities on the order of 5,000 feet per second for depleted uranium and 26,000 feet per second for shaped copper cones to achieve the intended effects on a target. Residual dust and debris from these weapons can carry latent effects that may be harmful.
Social organizations, such as the Campaign Against Depleted Uranium, have represented that there are latent dangers of depleted uranium to the health of the general population and to war fighters in particular. These dangers are latent, occurring well after the warhead has been expended or exposed to destabilizing environments such as a fire. It has been demonstrated that each of these types of warheads have sufficient chemical energy and kinetic energy to destroy the targets engaged, produce collateral damage beyond the area of the target, scatter hazardous debris in the form of depleted uranium dust and fragments, and to distribute a large number of unexploded submunitions, or even a single substantial unexploded unitary warhead.
By way of example, a shaped charge anti-armor warhead having a copper cone liner of a half pound traveling at a hypersonic velocity of 26,000 feet per second will penetrate 300 millimeters of roll hardened armor and has kinetic energy on the order of:K.E.=½(0.5/32.2)*(26,000)2=5.25×106 ft-lbs,wherein the kinetic energy (“K.E.”)=½ mv2=½(w/G)v2. In each of the computations herein, weight (w) is provided in units of pounds force, acceleration of gravity (G) is provided in units of feet per second and speed (v) is provided in units of feet per second resulting in kinetic energy with units of foot-pounds. A portion of the penetration capability of a shaped charge is produced by the very high temperature of the jet of gases formed by chemical explosive, on the order of thousands of degrees Fahrenheit, which drives the deformed copper liner into the armor.
A depleted uranium armor piercing projectile of ten pounds traveling at a velocity of 5,000 feet per second will pass completely through the turret of a main battle tank and has kinetic energy on the order of:K.E.=½(10/32.2)*(5000)2=3.88×106 ft-lbs.Continuing this example, by comparison, a guided bomb of 2000 pounds traveling above sonic velocity at 1392 feet per second has kinetic energy on the order of:K.E.=½(2000/32.2)*(1392)2=60.18×106 ft-lbs.
By way of comparison of the kinetic energy in the results of the guided bomb as compared to the results of the shaped charge and depleted uranium projectile, the guided bomb has a multiple of 11 to 15 or more times the kinetic energy. The kinetic energy of a guided 2000 pound bomb has the capability to penetrate several meters of reinforced concrete before the chemical explosive bursting charge detonates.
Destruction or neutralization of a target depends upon both the successful application of a warhead of sufficient energy, the ability to place the warhead on or within a suitable distance of the target and the fuzing of the warhead. Application of an oversized warhead when placed within an acceptable distance of the target will normally result in the destruction or neutralization of the target. This substantially increases the opportunity to cause undesired and unnecessary collateral damage beyond the space occupied by the target. Application of a warhead of insufficient size normally results in a failed attempt to destroy or neutralize the target, and these results may be independent of the placement of the warhead. For purposes of illustration, a nuclear warhead placed and detonated in close proximity to a main battle tank will result in the destruction of the tank. The collateral damage from the application would be extensive. In contrast, a bullet fired from a side arm (e.g., a pistol) would not likely destroy or neutralize a main battle tank, but there would be almost no collateral damage.
In a like manner, placement of the warhead significantly influences the results achieved. The greater the precision of placement of a warhead with respect to the target, the smaller the warhead that can be employed to achieve acceptable levels of destruction or neutralization of the target. Increased precision of warhead placement also reduces the opportunity for collateral damage. Political demands, ethical considerations, social influences and economic constraints on the rules of engagement are such that collateral damage is undesirable. Likewise, a large class of targets that are now encountered in current scenarios can be successfully defeated with smaller warheads with improved placement provided that the target detectors and warhead fuzing can suitably interpret target information such as location, motion and physical characteristics.
The vast multitude of targets that may be encountered in a given scenario requires a large matrix of warheads. Additionally, variability in target characteristics has lead to an introduction of a large number of diverse target sensors. Also, lasers, radar, multi-millimeter wave, infrared signals, geometric characteristics, acoustics noises, physical location and other methods are used to provide guidance and fuzing information to a warhead. This multi-parameter matrix of warheads, guidance systems, and rules of engagement results in a logistically difficult and large solution space to be properly managed so as to result in the effective destruction of the intended target without unacceptable collateral damage.
Current warhead technology is typically embodied in single effect munitions and does not incorporate a method of selectively varying effects. To be able to engage a large matrix of targets effectively requires a large mix of warheads. Limited magazine space and transportation capacity results in limited numbers of a given class of warheads or a limited mix of classes being available at the operating units. The available warhead load-out is limited by the possible warhead characteristics. Armed units entering a combat situation not having full knowledge of potential target characteristics or assigned a target-of-opportunity role typically elect to arm with warheads that yield the larger effects. The potential for mismatch between the target to be confronted and the load-out of the engaging unit is considerable. Thus, load-outs will tend to err on the side of larger warheads. Larger warheads affect larger areas and, in general, greatly increase the chances of collateral damage.
For purpose of example, consider an air-to-ground, guided missile (“AGM”) such as an AGM-154 configured with 145 submunitions (i.e., bomblets) dispensing the submunitions over an area as large as or larger than that of a football field. A percentage of dispensed submunitions (typically three to seven percent) fail to function resulting in a large number of unexploded submunitions creating hazards to friendly troops moving through the area, to innocent civilians, and to personnel removing the unexploded submunitions.
As an additional example, consider the application of a guided bomb unit (“GBU”) such as a GBU-28 (a precision-guided weapon with a 2000 pound class unitary warhead) to a civilian style structure embedded within a neighborhood. This type of warhead will generate collateral damage beyond the confines of the target engaged. Also, a GBU-28 that has been delivered but has failed to explode and may be subject to unintended motion, shock or impact presents a very significant latent hazard.
As a further example, consider the engagement of a non-armor vehicle or a civilian vehicle with a Hellfire missile. The blast energy far exceeds what is necessary to destroy that vehicle. Alternatively, a depleted uranium enhanced tank round would pass completely through the target and may not destroy or even seriously disable the target while at the same time producing unintended damage or destruction of unintended objects or individuals beyond the target.
It would be advantageous, therefore, to employ a warhead, weapon and weapon system that increases the size of the set of objects and features that is available for targeting. That is, weapons that augment the magnitude of the target region of FIG. 1. A weapon that can utilize the advantages of precision guidance and that has selectable effects with sufficient kinetic energy to destroy, neutralize or impair the selected target without substantially inducing either collateral damage or depositing hazardous debris or elements that have lingering latent injurious effects would be very advantageous. It would further be beneficial to deploy a warhead that detonates in a manner such that no or little conditions of unexploded ordnance occur. In the case of a weapon with little or no chemical explosives, the warhead can be used to attack a very wide spectrum of soft and hard targets and, in particular, attack targets that currently defy contact fuzing. The zone affected by the action of the warhead should remain within the impact area and within the CEP, and the existence of ancillary unexploded ordnance should be reduced.
Those skilled in the art appreciate that unitary warheads, submunitions and penetrating projectiles are packaged in a multitude of different shapes and containers thereby producing warheads that are compatible with many different methods of delivery such as, but not limited to, artillery shells, aircraft free fall bombs, guided and unguided rockets. Even in view of the flexibility, however, several limitations still apply to the application of such weapons such as a limited target set, collateral damage beyond the intended target, the production of residual latent dangerous and hazardous materials and debris including, but not limited to, unexploded ordnance, and the inability to select different effects from a single warhead.
Accordingly, what is needed in the art is an effective weapon and warhead that is adequate for the mission and very limited and specific to its area of intended destruction. The destructive force of the warhead should be confined to the intended target without inflicting damage to adjacent and non targeted structures, features, and innocent personnel. Additionally, the warhead should be substantially insensitive to stressing environments to significantly reduce the exposure to inadvertent explosion.